1. Field of the Invention
The present invention relates to an assistant standing seat, and more particularly to the assistant standing seat capable of assisting a user to change from a sitting posture to a standing posture easily, so as to reduce the burden exerted onto the user's knee and the force expended.
2. Brief Description of the Related Art
A knee joint is one of the most frequently moving parts of a human body, and many movements, such as walking, running, jumping, squatting, and kneeling, require the assistance and coordination of the knee joint to complete a smooth movement. However, our body and organs will become deteriorated due to aging, and there is no exception to the knee joint. Many people are suffered for knee joint problem caused by injury or a long-time use of the knee joint, such that they feel pain of knee joint during a movement, and the knee joint may not be bent or moved easily. Therefore, the knee joint pain is a troublesome problem to many people, regardless of they are male, female, young or old.
In the movements of our daily life, the knee joint is one of the very important joints. For example, switching sitting posture and a standing posture requires the use of the knee joint, and thus patients with a knee joint problem will feel painful and uncomfortable when they change postures between a sitting position and a standing position. Therefore, related manufacturers produce medical devices or accessories to help patients to reduce the pain and discomfort caused by changing their postures.
A portable occupant-arising assist chair with torsion springs as disclosed in U.S. Pat. No. 5,116,100 is placed on a soft chair such as an easy chair or sofa to help its user in being seated an arising, includes a rigid U-shaped lower frame that is spanned by a sheet of pliable material that is in contact with the seat, and further includes an upper U-shaped frame formed of tubing that is spanned by a rigid panel. The upper frame is resiliently and pivotally mounted to the lower frame by means of left and right torsion springs, which apply an upward force to the rigid panel to facilitate the user to sit down or arise.
A portable seating assist device as disclosed in U.S. Pat. No. 5,316,370 can be used in different chairs and furniture to facilitate users to change from a sitting posture to a standing posture, wherein the portable seating assist device comprises a base portion placed on the horizontal surface of a chair, a seating surface hingedly mounted to the base, and a compression spring mounted between the seating surface and the base to urge the two apart and allow an upwardly assisted motion between a closed and open position, so as to allow a user to stand up gradually from a sitting posture and reduce the burden exerted onto the knee joint.
However, the portable occupant-arising assist chair and the portable seating assist device are not suitable for an over-weight user. Since this device just uses a compression spring or a torsion spring as a lifting force source to provide a rising force for the elevation, and the rising force varies (or becomes weaker) with the condition of spreading open the portable seating assist device. Therefore, the compression spring is usually insufficient to support overweight users.
As disclosed in Pat. Application No. US 2003/090135 (A1), the electric seat assist device comprises: a base, a seat pivotally secured to a forward portion of the base, a scissors mechanism for use in moving the seat relative to the base, and the scissors mechanism including at least one upper cam surface extending from the bottom of the seat, a lower cam surface extending upwardly from the base, an electric control module using an electric motor as a force source, and being positioned between the upper and lower cam surfaces, and drive means for moving the seat with respect to the base to facilitate a user to change postures between a sitting posture and a standing posture.
The electric seat assist device uses the electric motor as the force source to overcome the drawback of the compression spring used in the portable seating assist device, and allow a user to apply a certain force in the process of changing postures from the sitting posture to the standing posture to assist the user to stand up. However, the scissors mechanism of the electric seat assist device has to fully support the weight of the user. Therefore, the weight of the user directly increases the resistance of the scissors mechanism that can move between the base and the seat. As a result, the electric seat assist device cannot be elevated easily.
Regardless of the portable seating assist device as disclosed in U.S. Pat. No. 5,316,370 or the electric seat assist device as disclosed in the U.S. Pat. Application No. US 2003/090135 (A1), the assist devices are insufficient for overweight users. Obviously, the structures of the conventional seats still require improvements.